Medical implant extraction device

ABSTRACT

Extraction instruments and systems for use in revision arthroplasty are provided. The extraction instruments are shaped and configured to fit within the typically tight confines in which revision arthroplasty is performed, and to enhance the surgeon&#39;s control over the axis, quantum and speed of the force that is required be applied to disrupt a bone-to-prosthesis bond. This enables completion of a revision arthroplasty to proceed more quickly, and with reduced risk that unwanted movements might cause accidental injury to nearby vital structures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/341,785 filed on Apr. 5, 2010, priority from thefiling date of which is claimed under 35 U.S.C. §119, and which ishereby fully incorporated by reference.

TECHNICAL FIELD

The subject matter described herein relates in general to devices andsystems for use in orthopedic surgery, and more particularly to revisionarthroplasty.

BACKGROUND

Arthroplasty is a surgical procedure in which an arthritic ordysfunctional joint surface is replaced with an orthopedic prosthesis.By way of example, in a total knee arthroplasty, the patient's femoraland tibial bones are contoured for receiving prosthetic implants, andthree component prosthetic parts (femoral, tibial, and patella) areimplanted.

For optimal function, a strong bond between the patient's natural boneand the metal or plastic components of the implanted prosthesis must beachieved. Fixation features such as cement (e.g. methyl methacrolatecompounds), surface textures that enhance natural bone ingrowth, and/orfixation pegs or similar structures are typically employed to achievethis strong bond.

If an implant fails to function correctly or becomes infected, revisionsurgery (known as revision arthroplasty) is normally required. Revisionarthroplasty generally involves the removal of a previously-implantedprosthetic joint, and the replacement thereof with a new prosthesis.During this procedure, the surgeon may remove some or all of theimplanted component parts of the affected prosthesis.

Removal of the previously-implanted prosthesis requires disruption ofthe strong existing bone-to-prosthesis bond (which may be facilitated orenhanced by fixation features of the sort described above), and theproximity of vulnerable anatomic structures such as blood vessels andnerves in the typically tight confines of space within which thedisruptive force must be applied may pose difficulties for the surgeonand may make removal of the implanted components potentially hazardousto the patient. In particular, since the disruption of all or a portionof the bone-to-prosthesis bond typically occurs rather suddenly, it isnot uncommon at the moment of disruption for the instrument that isbeing used to apply the disruptive force to move in the direction of theforce applied in a somewhat uncontrolled manner for a variable distance,despite the best efforts and skill of the operating surgeon to limitthis movement.

Various design characteristics of prosthetic implants and othercircumstances may further exacerbate these difficulties and hazards,including the three-dimensional configuration of the prostheticimplants, the existence of a multiplicity of different sizes ofprosthetic implants, and the buildup of scar tissue around apreviously-implanted prosthesis, which can make it difficult to gain thenecessary exposure of the bonded interface between natural bone andimplanted component. The overall complexity associated with the saferemoval of implants using known instruments and methods may accordinglyresult in a long operative procedure and consequent long duration ofanaesthetic administered to the patient.

The three-dimensional configuration of a prosthetic implant is generallyselected so as to optimize the functionality of the implant, as well asthe ability to achieve a strong bone-to-prosthesis bond. Thebone-contacting surface of a prosthetic implant component mayaccordingly comprise complex shapes that include curved, angled and flatsurfaces of various dimensions, as well as pegs or other fixationfeatures of the sort discussed above, which co-operate withcomplementary bone surface features and structure that are created bythe surgeon to accept the component during implantation.

By way of example, the tibial component of a knee joint prosthesis mayinclude multiple pegs or a broad single stem, or a combination thereof.

Heretofore, the orthopedic instruments that have been used by orthopedicsurgeons to remove implanted prosthetic components during a revisionarthroplasty have included thin flexible single end cutting osteotomes,solid single end cutting osteotomes, jiggly saws, oscillating saws andreciprocating saws. These instruments are in many cases functionallylimited in that they are either too broad, too thick and/or otherwiseunable to fit within the tight confines of a typical revisionarthroplasty. Their use therefore, although necessary, challenges thesurgeon's abilities to deliver strong but controlled forces in a varietyof directions, as is usually required to disrupt the bond, but to limitunwanted residual movement of the cutting edge immediately afterdisruption occurs. The use of these known instruments may accordinglyalso result in the removal of excess quantities of the patient'sessential bone during a revision arthroplasty, leaving undesirably largecavities or bone gaps that could potentially compromise the success ofthe revision surgery. When removing pre-existing implants which havebeen in the patient for a number of years, maximization of bonepreservation is especially important.

Prior-known osteotomes are typically used during revision arthroplastyin a chisel-like fashion, accomplished primarily by the application offorce in an axial manner using a mallet or similar instrument to strikethe distal end of the osteotome and thereby to drive the knife endthereof between the prosthetic component and the host bone. Multipleblows, usually of increasing force, are typically required to weaken andeventually disrupt the bone-to-prosthesis bond. However, as noted above,when the bond is finally broken by the repetitive hammer applications,the residual axial force after disruption may result in a sudden andsomewhat uncontrolled movement of the cutting surface of the osteotomein the direction of the applied force. With currently known orthopedicinstruments, including osteotomes and saws, this direction of appliedforce (and the resulting possible uncontrolled movement) is typicallytowards body of the patient and the important anatomical structureswithin (e.g. the blood vessels and nerves at the back of a knee joint),thereby increasing the risk of inadvertent injury.

There is accordingly a need for effective devices and methods for use inorthopedic surgery that may simplify and/or expedite the progress of arevision arthroplasty while minimizing the risk of inadvertent injuryand/or the removal of excess host bone. In addition, there is a need fora universal system, assembly or kit of orthopedic devices thatfacilitates safe, controlled prosthetic component removal, and that isapplicable to all or a variety of different implanted componentprosthetic designs.

SUMMARY

This summary is not an extensive overview intended to delineate thescope of the subject matter that is described and claimed herein. Thesummary presents aspects of the subject matter in a simplified form toprovide a basic understanding thereof, as a prelude to the detaileddescription that is presented below.

Embodiments of the subject matter described and claimed herein providedevices and methods for use in the disruption of a bone-to-prosthesisbond during revision arthroplasty. The devices generally compriseextraction instruments that are shaped and configured to fit within thetypically tight confines in which revision arthroplasty is performed,and to enhance the surgeon's control over the axis, quantum and speed ofthe force that must be applied to disrupt the bond. This enables thesurgeon to complete the revision arthroplasty more quickly, and withreduced risk that unwanted movements might cause accidental injury tonearby vital structures. The presently disclosed devices are fabricatedof stainless steel, titanium, or any other material known to those ofskill in the art to be suitable for the construction of surgicalinstruments, and may also be inherently safer than prior-knownosteotomes in that the cutting edges thereof need not be as sharp asthose of prior-known osteotomes.

In some embodiments, the described devices enable the application ofreverse axial forces (i.e. in a direction that is away from the body ofthe patient) and/or make use of pivot points provided in the shaft orthe extraction blades thereof in order to interact with the implantedprosthesis directly, and thereby to provide leverage and mechanicaladvantage, and improved control to reduce the risk of inadvertent injuryand/or excess bone loss. Varying cross-sections of the extractionblades, such as for example convex or skewed convex cross-sections, mayalso be provided in some embodiments in order to further enhance thesurgeon's control over the accurate application and direction ofdisruptive forces by providing a positive directional bias towards theunderside of the implanted prosthesis, and by reducing the contactsurface area between the device and implant during use.

In one preferred embodiment, the device comprises a generally hook orJ-shaped extraction instrument comprising an elongate shaft having adistal end and a proximal end, and an elongate reverse extraction bladeconnected to and spaced apart from the distal end of the shaft by abridge, the reverse extraction blade being generally planar or convex incross-section and extending from the bridge generally parallel to andback in the direction towards the proximal end of the shaft, andcomprising at least one cutting edge disposed at the free end thereof.The extraction blade may be inclined at between roughly 0° and 45°relative to the longitudinal axis of the shaft, and may preferablyfurther comprise additional cutting edges disposed along either or bothof its longitudinal surfaces.

In another preferred embodiment, the device comprises a generallyL-shaped extraction instrument comprising an elongate shaft having adistal end and a proximal end, and a generally planar reverse extractionblade connected to the distal end of the shaft and extending generallyperpendicularly therefrom. The reverse extraction blade of thisembodiment has at least one cutting edge along the edge of the bladethat is closest to the proximal end of the shaft, and this at least onecutting edge may be angled inwards towards the shaft at an angle ofbetween roughly 75° to 120° in order to reduce the tendency of theL-shaped extraction instrument to slip perpendicularly during use. Anotch may also in some embodiments be formed in the cutting edge tofacilitate pivotal action of the L-shaped extraction instrument relativeto selected features of an implanted prosthetic component.

In other embodiments, the devices comprise extraction instruments, eachof which comprise an elongate shaft having a distal end and a proximalend, a pivot edge formed at or near the distal end of the shaft, and anelongate extraction blade connected to the pivot edge at one of avariety of inclinations and angles with respect thereto. The elongateextraction blades of each of these embodiments have at least one cuttingedge along at least one longitudinal surface thereof, and are relativelyshort as compared to the length of the shaft in order that pivotalmovement of the cutting instrument about the pivot edge will providereadily controllable leverage and mechanical advantage to the user. Arange of extraction instruments having different relative lengths ofshafts and elongate extraction blades may be provided, depending on theleverage and space requirements of varying applications.

The elongate shaft of the extraction instrument may further comprise ahandle element at or near its proximal end. The handle may be integralwith the elongate shaft, or may alternatively be formed separately fromthe cutting instrument and either permanently affixed or removablyconnected at or near the proximal end of the shaft in any of the manysuitable manners known to those of skill in the art to provide apositive engagement in both an axial and rotational sense. Inembodiments where the handle is formed separately from the extractioninstrument, the handle may be fabricated of the same material as theextraction instrument, or from any other material known to those ofskill in the art to be suitable for the construction of surgicalinstruments.

In some preferred embodiments, the device further comprises a reverseforce hammer (conventionally known as a “slap hammer”) that includes amovable weight with an interior aperture sized for the slidableengagement of the shaft of the extraction instrument, and which islimited in its range of travel towards the distal end of the shaft byeither the handle or by a separate striking plate connected to eitherthe handle or to the shaft of the extraction instrument. When the slaphammer is moved sharply towards the proximal end of the shaft andcollides with either the handle or the striking plate, a force isapplied along the axis of the extraction instrument in the proximaldirection. This force is 180° reversed from the force that is normallyapplied to a prior-known osteotome by a conventional hammer.

Also described and claimed herein is a system, assembly and kit ofextraction instruments, each extraction instrument having a differentextraction blade, and each extraction instrument facilitating theapplication of disruptive force in a previously undisclosed manner withassociated functional advantages as described in further detail hereinbelow. For convenience, the claimed subject matter is described by wayof example but not limitation in the detailed description provided belowin relation to a system of devices suitable for use primarily inrevision knee arthroplasty. However, it would of course be readilyapparent to those of skill in the art that the advantages afforded bythe subject matter that is described and claimed herein are not limitedto any specific joint revision.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of the disclosedsubject matter, as well as the preferred mode of use thereof, referenceshould be made to the following detailed description, read inconjunction with the accompanying drawings. In the drawings, likereference numerals designate like or similar steps or components.

FIG. 1 is a perspective view of a representative knee joint prosthesisillustrating the relative placement of implanted femoral and tibialprosthetic components.

FIG. 2 is a bottom plan view of a representative tibial prostheticcomponent illustrating a typical arrangement of fixation pegs.

FIG. 3 is a top plan view of an extraction instrument in accordance withan embodiment of the disclosed subject matter.

FIG. 4 is front elevation of the extraction instrument of FIG. 3.

FIG. 5 is a top plan view of an extraction instrument in accordance withan embodiment of the disclosed subject matter.

FIG. 6 is front elevation of the extraction instrument of FIG. 5.

FIG. 7 is a top plan view of an extraction instrument in accordance withan embodiment of the disclosed subject matter.

FIG. 8 is front elevation of the extraction instrument of FIG. 7.

FIG. 9 is a top plan view of an extraction instrument in accordance withan embodiment of the disclosed subject matter.

FIG. 10 is front elevation of the extraction instrument of FIG. 9.

FIG. 11 is a top plan view of an extraction instrument in accordancewith an embodiment of the disclosed subject matter.

FIG. 12 is front elevation of the extraction instrument of FIG. 11.

FIG. 13 is a top plan view of an extraction instrument in accordancewith an embodiment of the disclosed subject matter.

FIG. 14 is front elevation of the extraction instrument of FIG. 13.

FIG. 15 is a top plan view of an extraction instrument in accordancewith an embodiment of the disclosed subject matter, shown in combinationwith a handle and strike plate.

FIG. 16 is front elevation of the extraction instrument of FIG. 15.

FIG. 17 is a top plan view of an extraction instrument in accordancewith an embodiment of the disclosed subject matter, shown in combinationwith a handle, strike plate and slap hammer.

FIG. 18 is front elevation of the extraction instrument of FIG. 17.

FIG. 19 is a top plan view of a representative system or kit ofextraction instruments suitable for use primarily in revision kneearthroplasty.

FIGS. 20A-20H are enlarged cross-sectional end views of the extractionblade of extraction instruments in accordance with embodiments of thedisclosed subject matter.

FIGS. 21-28 are representative perspective views illustrating theinteraction between extraction instruments in accordance withembodiments of the disclosed subject matter and representative tibialprosthetic components.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

As previously noted, the claimed subject matter is illustrated anddescribed herein by way of example but not limitation in relation to asystem of devices suitable for use primarily in revision arthroplasty ofa knee joint. However, it would of course be readily apparent to thoseof skill in the art that the advantages afforded by the subject matterthat is described and claimed herein are not limited to any specificjoint revision.

FIG. 1 illustrates representative a knee joint prosthesis 1 showing therelative placement of implanted femoral prosthetic component 2 andtibial prosthetic component 3, and FIG. 2 is a bottom plan view of arepresentative tibial prosthetic component 3 illustrating a typicalarrangement of fixation pegs 4.

Six representative extraction instruments are illustrated in FIGS. 3-14,each of which is shaped and configured to fit within the typically tightconfines in which revision arthroplasty is performed, and to enhance thesurgeon's control over the axis, quantum and speed of the force thatmust be applied to disrupt the strong bond that exists between apreviously-implanted prosthetic component and the host bone of thepatient. Other configurations of extraction instruments that are withinthe scope of the present disclosure will, of course, be readily apparentto those of skill in the art from an understanding of the principlesthat underlie the presently-disclosed subject matter.

With reference to FIGS. 3 and 4, there is illustrated a generally hookor J-shaped extraction instrument 10 comprising an elongate shaft 11having a distal end 12 and a proximal end 13, and an elongate reverseextraction blade 14 connected to and spaced apart from the distal end 12of the shaft 11 by a bridge 15. The reverse extraction blade 14 extendsfrom the bridge 15 generally parallel to and back in the directiontowards proximal end 13 of the shaft 11, and comprises sharp tip 16 andtapered sharp lateral edges 17 and 18.

The surface 19 of reverse extraction blade 14 is generally planar toslightly convex or skewed convex, with convex and skewed convexconfigurations providing a positive directional bias towards theunderside of the implant during use, as well as reducing the contactsurface area of the reverse extraction blade 14. Alternativerepresentative embodiments of each of the generally planar, convex andskewed convex cross-sections of reverse extraction blade 14 areillustrated, respectively, in FIGS. 20A-20H.

The elongate reverse extraction blade 14 may be inclined between roughly0° and 45° relative to the longitudinal axis of the shaft 11, andextraction instrument 10 may optionally further comprise a connector 19Aat the proximal end 13 of shaft 11 for connection to a strike plateand/or handle, as will be further described below.

The extraction instrument 10 is fabricated of stainless steel, titanium,or any other material known to those of skill in the art to be suitablefor the construction of surgical instruments, and in preferredembodiments that are useful in revision arthroplasty of the knee joint,reverse extraction blade 14 may be between about 0.5 mm to 5 mm thick,between about 5 mm to 35 mm long, and between about 3 mm to 20 mm widewhere it connects to the bridge 15, tapering down to about 19 mm to 0.1mm in width at sharp tip 16. The bridge 15 may separate the shaft 11 andreverse extraction blade 14 by between about 2 mm to 20 mm, and may beflat or rounded (i.e. convex or concave) in cross-section to facilitatepivoting of the reverse extraction blade 14 against the outer and inneredges or other features of the prosthetic component to be removed.

The cross-section of shaft 11 is preferably round but may be of anyother shape, and the overall dimension of the cross-section may rangefrom about 2 mm to 10 mm. The length of shaft 11 may range from about 20mm to 300 mm, and in any event will be selected to be sufficiently longto provide suitable access to the prosthetic component to be removed.

FIGS. 5 and 6 illustrate a generally L-shaped extraction instrument 20comprising an elongate shaft 21 having a distal end 22 and a proximalend 23, and a generally planar reverse extraction blade 24 connected tothe distal end 22 of the shaft 21 and extending generallyperpendicularly therefrom. The reverse extraction blade 24 has at leastone tapered sharp edge 25 along the edge of the blade 24 that is closestto the proximal end 23 of the shaft 21, and this at least one sharp edge25 is preferably angled inwards towards the shaft 21 at an angle ofbetween roughly 75° to 120° in order to reduce the tendency of theL-shaped extraction instrument to slip perpendicularly during use.L-shaped extraction instrument 20 may optionally further comprise aconnector 26 at the proximal end 23 of shaft 21 for connection to astrike plate and/or handle, as will be further described below.

The extraction instrument 20 is fabricated of stainless steel, titanium,or any other materials known to those of skill in the art to be suitablefor the construction of surgical instruments, and in preferredembodiments useful in revision arthroplasty of the knee joint, reverseextraction blade 24 may be between about 0.5 to 5 mm in thickness,between about 5 mm and 30 mm wide, and between about 3 mm to 15 mm indepth. The free edge 27 of reverse extraction blade 24 is preferablyflat, and a symmetrical or asymmetrical notch 28 may be provided insharp edge 25 of reverse extraction blade 24, or elsewhere on reverseextraction blade 24, in order to facilitate leveraging of extractioninstrument 20 in relation to a fixation peg 4 or other surface featureof an implanted prosthetic component.

The cross-section of shaft 21 is preferably round but may be of anyother shape, and the overall dimension of the cross-section may rangefrom about 2 mm to 10 mm. The length of shaft 21 may range from about 20mm to 300 mm, and in any event will be selected to be sufficiently longto provide suitable access to the prosthetic component to be removed.

FIGS. 7-13 illustrate four representative embodiments of extractioninstruments in which a pivot edge is provided at or near the proximalend of the shaft in order to facilitate the pivotal movement of theextraction instrument relative to a surface feature of the implantedprosthesis to be extracted, and thereby to provide increased mechanicaladvantage and improved control in the application of the force necessaryto disrupt the bone-to-prosthesis bond. The four representativeembodiments that are illustrated are preferred in relation to therevision arthroplasty of a knee joint, but as would be apparent to thoseof skill in the art, other configurations that are within the scope ofthe present disclosure are also possible. By way of example, the pivotpoint of an extraction instrument may be located at some other locationon the shaft, and may for example comprise a symmetrical or asymmetrical“notch” configured to interact with selected surface features of animplanted prosthetic component.

With reference to FIGS. 7 and 8, there is illustrated an extractioninstrument 30 comprising an elongate shaft 31 having a distal end 32 anda proximal end 33. A pivot edge 34 is formed at the distal end 32 of theshaft 31, and may be of generally convex, concave or planarconfiguration. A straight elongate extraction blade 35 comprising sharpor blunt tip 36 and tapered sharp lateral edges 37 and 38 is connectedat roughly a right angle to the face of the pivot edge 34, and extendsin the distal direction generally collinearly along the longitudinalaxis of shaft 31. The straight elongate extraction blade 35 may,however, also extend in some embodiments along a longitudinal axis thatis offset from that of shaft 31 so as to enhance clearance. The surface39 of straight elongate extraction blade 35 is generally planar, convexor skewed convex in cross-section, with convex configurations providinga positive directional bias towards the underside of the implant duringuse, as well as reducing the contact surface area of the straightelongate extraction blade 35. Alternative representative embodiments ofeach of the generally planar, convex and skewed convex cross-sections ofstraight elongate extraction blade 35 are illustrated, respectively, inFIGS. 20A-20H. Extraction instrument 30 may optionally further comprisea connector 39A at the proximal end 33 of shaft 31 for connection to astrike plate and/or handle, as will be further described below.

The extraction instrument 30 is fabricated of stainless steel, titanium,or any other materials known to those of skill in the art to be suitablefor the construction of surgical instruments, and in preferredembodiments useful in revision arthroplasty of the knee joint, straightelongate extraction blade 35 may be between about 0.5 mm to 5 mm thick,between about 5 mm to 60 mm long, and between about 3 mm to 20 mm widewhere it connects to the pivot edge 34, tapering down to about 19 mm to0.1 mm in width at tip 36. The pivot edge 34 is between about 0 mm(flush) and 15 mm in height (as measured perpendicularly to thelongitudinal axis of the shaft 31), and may be flat or rounded (i.e.convex or concave) to facilitate pivoting of the straight elongateextraction blade 35 against the outer and inner edges or other featuresof the prosthetic component to be removed.

The cross-section of shaft 31 is preferably round but may be of anyother shape, and the overall dimension of the cross-section may rangefrom about 2 mm to 10 mm. The length of shaft 31 may range from about 20mm to 300 mm, and in any event will be selected to be sufficiently longto provide suitable access to the prosthetic component to be removed.

FIGS. 9 and 10 illustrate an extraction instrument 40 comprising anelongate shaft 41 having a distal end 42 and a proximal end 43. A pivotedge 44 is formed at the distal end 42 of the shaft 41 at an anglerelative to the longitudinal axis of the shaft 41, and may be ofgenerally convex, concave or flat configuration. An elongate extractionblade 45 comprising tip 46 and tapered sharp lateral edges 47 and 48 isconnected at roughly a right angle to the face of the pivot edge 44 andextends in the distal direction at an angle through the longitudinalaxis of the shaft 41. The surface 49 of elongate extraction blade 45 isgenerally planar, convex or skewed convex in cross-section, with convexconfigurations providing a positive directional bias towards theunderside of the implant during use, as well as reducing the contactsurface area of the elongate extraction blade 45. Alternativerepresentative embodiments of each of the generally planar, convex andskewed convex cross-sections of elongate extraction blade 45 areillustrated, respectively, in FIGS. 20A-20H. Extraction instrument 40may optionally further comprise a connector 49A at the distal end 43 ofshaft 41 for connection to a strike plate and/or handle, as will befurther described below.

The extraction instrument 40 is fabricated of stainless steel, titanium,or any other materials known to those of skill in the art to be suitablefor the construction of surgical instruments, and in preferredembodiments useful in revision arthroplasty of the knee joint, elongateextraction blade 45 may be between about 0.5 mm to 5 mm thick, betweenabout 5 mm to 25 mm long, and between about 3 mm to 15 mm wide where itconnects to the pivot edge 44, tapering down to about 14 mm to 0.1 mm inwidth at tip 46. The pivot edge 44 is between about 0 mm (flush) and 15mm in height (as measured perpendicularly to the longitudinal axis ofthe shaft 41), and may be flat or rounded (i.e. convex or concave) tofacilitate pivoting of the elongate extraction blade 45 against theouter and inner edges of the prosthetic component to be removed.

The cross-section of shaft 41 is preferably round but may be of anyother shape, and the overall dimension of the cross-section may rangefrom about 2 mm to 10 mm. The length of shaft 41 may range from about 20mm to 300 mm, and in any event will be selected to be sufficiently longto provide access to the prosthetic component to be removed.

FIGS. 11 and 12 illustrate an extraction instrument 50 comprising anelongate shaft 51 having a distal end 52 and a proximal end 53. Distalend 52 of shaft 51 is curved at an angle relative to the overalllongitudinal axis of the shaft 51, and has a pivot edge 54 formed at theend thereof. The pivot edge 54 may be of convex, concave or flatconfiguration, and an elongate extraction blade 55 comprising tip 56 andtapered sharp lateral edges 57 and 58 is connected at roughly a rightangle to the face of the pivot edge 54 and extends in the proximaldirection at an angle through the longitudinal axis of the shaft 51. Thesurface 59 of elongate extraction blade 55 is generally planar, convexor skewed convex in cross-section, with convex configurations providinga positive directional bias towards the underside of the implant duringuse, as well as reducing the contact surface area of the straightelongate extraction blade 55. Alternative representative embodiments ofeach of the generally planar, convex and skewed convex cross-sections ofelongate extraction blade 55 are illustrated, respectively, in FIGS.20A-20H. Extraction instrument 50 may further optionally comprise aconnector 59A at the proximal end 53 of shaft 51 for connection to astrike plate and/or handle, as will be further described below.

The extraction instrument 50 is fabricated of stainless steel, titanium,or any other materials known to those of skill in the art to be suitablefor the construction of surgical instruments, and in preferredembodiments useful in revision arthroplasty of the knee joint, elongateextraction blade 55 may be between about 0.5 mm to 5 mm thick, betweenabout 5 mm to 25 mm long, and between about 3 mm to 15 mm wide where itconnects to the pivot edge 54, tapering down to about 14 mm to 0.1 mm inwidth at tip 56. The pivot edge 54 is between about 0 mm (flush) and 15mm in height (as measured perpendicularly to the longitudinal axis ofthe shaft 51), and may be flat or rounded (i.e. convex or concave) tofacilitate pivoting of the elongate extraction blade 55 against theouter and inner edges or other features of the prosthetic component tobe removed. As illustrated in FIG. 12, pivot edge 54 may also be“hook-shaped” in order to reduce the possibility of slippage of theextraction instrument 50 relative to blade the prosthetic componentduring the application of force. The pivot edges of other embodiments ofthe extraction instrument may similarly be “hook-shaped” inconfiguration.

The cross-section of shaft 51 is preferably round but may be of anyother shape, and the overall dimension of the cross-section may rangefrom about 2 mm to 10 mm. The length of shaft 51 may range from about 20mm to 300 mm, and in any event will be selected to be sufficiently longto provide access to the prosthetic component to be removed.

FIGS. 13 and 14 illustrate an extraction instrument 60 comprising anelongate shaft 61 having a distal end 62 and a proximal end 63. A pivotedge 64 is formed at the distal end 62 of the shaft 61, and may beconvex, concave or flat configuration. A side angled elongate extractionblade 65 comprising tip 66 and tapered sharp lateral edges 67 and 68 isconnected at between roughly 0° and 90°, and most preferably around 45°laterally relative to the longitudinal axis of the shaft 61, and atroughly a right angle to the face of the pivot edge 64. The surface 69of side angled elongate extraction blade 65 is generally planar, convexor skewed convex in cross-section, with convex configurations providinga positive directional bias towards the underside of the implant duringuse, as well as reducing the contact surface area of the straightelongate extraction blade 65. Alternative representative embodiments ofeach of the generally planar, convex and skewed convex cross-sections ofside angled elongate extraction blade 65 are illustrated, respectively,in FIGS. 20A-20H. Extraction instrument 60 may further optionallycomprise a connector 69A at the proximal end 63 of shaft 61 forconnection to a strike plate and/or handle, as will be further describedbelow.

The extraction instrument 60 is fabricated of stainless steel, titanium,or any other materials known to those of skill in the art to be suitablefor the construction of surgical instruments, and in preferredembodiments useful in revision arthroplasty of the knee joint, and sideangled elongate extraction blade may be between about 0.5 mm to 5 mmthick, between about 5 mm to 25 mm long, and between about 3 mm to 20 mmwide where it connects to the pivot edge 64, tapering down to about 19mm to 0.1 mm in width at sharp tip 66. The pivot edge 64 is betweenabout 0 mm (flush) and 15 mm in height (as measured perpendicularly tothe longitudinal axis of the shaft 41), and may be flat or rounded (i.e.convex or concave) to facilitate pivoting of the elongate extractionblade 65 against the outer and inner edges or other features of theprosthetic component to be removed.

The cross-section of shaft 61 is preferably round but may be of anyother shape, and the overall dimension of the cross-section may rangefrom about 2 mm to 10 mm. The length of shaft 61 may range from about 20mm to 300 mm, and in any event will be selected to be sufficiently longto provide access to the prosthetic component to be removed.

As previously described, the extraction instruments of FIGS. 3-14 mayfurther comprise integrally formed handle and/or strike plate elementsat or near their proximal ends, or may alternatively be configured witha suitable connector (i.e. connector 19A, 26, 39A, 49A, 59A or 69A) ator near their proximal ends for the permanent or removable connection ofa separately-formed strike plate and/or handle. The connection may beeffected in any conventional manner known to those of skill in the artto provide a positive engagement in both an axial and rotational sense.By way of example, complementary male and female threads may be providedin the handle and at the distal end of the extraction instrument shaftin order to provide a positive engagement in an axial sense, andcomplementary protrusions and mating recesses or the like may also beprovided in the handle and at the distal end of the extractioninstrument shaft to provide rotational stabilization.

In some preferred embodiments, particularly in relation to embodimentsin which the extraction instrument comprises a reverse extraction blade,a reverse force hammer (conventionally known as a “slap hammer”) thatcomprises a movable weight with an interior aperture sized for theslidable engagement of the shaft of the extraction instrument, and whichis limited in its range of travel towards the proximal end of the shaftby the handle or by a separate striking plate connected to either thehandle or to the shaft of the extraction instrument, may also be alsoprovided. Alternatively, connectors 19A, 26, 39A, 49A, 59A and/or 69Amay be configured for attachment of a conventional slap hammer assembly.The strike plate, handle and/or slap hammer may be fabricated from thesame material as the cutting instruments, or from any material known tothose of skill in the art to be suitable for the construction ofsurgical instruments.

FIGS. 15 and 16 illustrate a representative assembly of the extractioninstrument of FIGS. 3 and 4 in combination with a strike plate andhandle, and FIGS. 17 and 18 illustrate a representative assembly of theextraction instrument of FIGS. 5 and 6 in combination with a strikeplate, handle and slap hammer. Although not illustrated, it would ofcourse be readily apparent to those of skill in the art that assembliesof the extraction instruments of FIGS. 7 through 14 together withhandles, strike plates and/or slap hammers may similarly be constructed.

In FIGS. 15 and 16, the combination J-shaped extraction instrument,strike plate and handle are generally indicated by reference numeral 80.Combination instrument 80 comprises an elongate shaft 81 having anelongate reverse extraction blade 84 connected to and spaced apart froma first end of the shaft 81 by a bridge 85. Strike plate 87 and handle88 are attached permanently or releasably via connector 19A (see FIG. 4)at the second end of shaft 81 and mating connectors on each of thestrike plate 87 and handle 88. Alternatively, as discussed above, strikeplate 87 and/or handle 88 may be formed integrally with shaft 81.

As with the extraction instrument of FIGS. 3 and 4, the elongate reverseextraction blade 84 extends from the bridge 85 generally parallel to andback in the direction towards the second end and the strike plate 87 andhandle 88, and comprises tip 86 and tapered sharp lateral edges 82 and83. The surface 89 of reverse extraction blade 84 is generally planar toslightly convex or skewed convex, with convex configurations providing apositive directional bias towards the underside of the implant duringuse, as well as reducing the contact surface area of the reverseextraction blade 84. Alternative representative embodiments of each ofthe generally planar, convex and skewed convex cross-sections of reverseextraction blade 84 are illustrated, respectively, in FIGS. 20A-20H.

A combination L-shaped extraction instrument, strike plate, handle andslap hammer is generally indicated by reference numeral 90 in FIGS. 17and 18. Combination instrument 90 comprises an elongate shaft 91 havinga generally planar reverse extraction blade 92 connected to a first endof the shaft 91, and a handle 94 and strike plate 95 attachedpermanently or releasably via connector 26 (see FIG. 6) at the secondend of shaft 91 and mating connectors on each of the handle 94 andstrike plate 95. Slap hammer 96 comprises a movable weigh that isslidably engaged on shaft 91 and limited in its range of travel towardsthe second end of shaft 91 by the strike plate 95 and/or handle 94. Inalternative embodiments, such as where additional room for travel ofslap hammer 96 is desired, the combination extraction instrument maycomprise only a strike plate (i.e. without a handle) attached at thesecond end of shaft 91.

The reverse extraction blade 92 has at least one tapered sharp edge 93along the edge of the blade 92 that is closest to the second end of theshaft 91, and this at least one sharp edge 93 is preferably beveled ortapered inwards towards the shaft 91 at an angle of between roughly 75°to 120° in order to reduce the tendency of the L-shaped extractioninstrument to slip perpendicularly during use, such as when the slaphammer 96 is moved sharply towards the second end of the shaft 91 andcollides with either the striking plate 95 or handle 94.

Referring now to FIG. 19, there is illustrated in a top plan view arepresentative system and kit of extraction instruments suitable for useprimarily in revision knee arthroplasty. The system and kit compriseJ-shaped reverse extraction instrument 10 of FIG. 3, the L-shapedextraction instrument 20 of FIG. 5, and one or more of each of pivotalextraction instruments 30, 40 and 60 of FIGS. 7, 9 and 13, respectively.Also included in the system and kit are one or more of each ofdetachable handle 100 and slap hammer 110. In combination, thecomponents of the system and kit of FIG. 19 facilitate the ability of asurgeon to apply controlled forces in a variety of axes, includingreverse, and to utilize a variety of pivot points in conjunction withthe implanted components being removed in order to provide controlledleverage and mechanical advantage, and thereby enhance both the speedand safety of a knee revision arthroscopy. Of course, as would bereadily apparent to those of skill in the art from an understanding ofthe principles that underlie the presently-disclosed subject matter,other systems and kits that include more, fewer or different componentparts (such as, for example, integral combination extractioninstruments), and systems intended to be particularly suitable for therevision arthroscopy of various other joints may be constructed.

FIGS. 21-28 illustrate in representative fashion the application ofreverse cutting edges and forces, and the use of a variety of pivotpoints to enhance control in the application of forces in the engagementof representative examples of the extraction instruments of FIGS. 3-14and the edges, surfaces and other three-dimensional features of aprosthetic component to be removed.

In FIGS. 21-22, the extraction instrument of FIGS. 13 and 14 is shownwith its pivot edge abutting the side surface of a representative tibialprosthetic component, and with its extraction blade abutting the bottomsurface of the prosthetic component as well as one of the fixation pegsof the component. In FIG. 23, the same extraction instrument is shownwith the pivot edge still abutting the side surface of the prostheticcomponent, but with its extraction blade abutting only the bottomsurface.

The fixation peg may accordingly be used in FIGS. 21 and 22, but not inFIG. 23, as a pivot point vis-à-vis the extraction blade to draw theextraction instrument generally along the bottom surface of theprosthesis in the direction marked “A”, and thereby to apply acontrolled force in the disruption of the bone-to-prosthesis bondadjacent to the corresponding edge of the extraction blade.Alternatively, the extraction instrument may be pivoted about its pivotedge in the direction marked “B” (in the examples of any of FIGS. 21-23)to disrupt in a controlled manner the bone-to-prosthesis bond adjacentto the opposite edge of the extraction blade. In either case, thepivotal movement of the extraction instrument relative to a surfacefeature of the prosthetic component facilitates increased leverage andmechanical advantage, and enables improved control in the application ofthe force necessary to disrupt the bone-to-prosthesis bond.

FIGS. 24 and 25 illustrate, respectively, the extraction instruments ofFIGS. 7 and 8, and of FIGS. 9 and 10, engaging a representative tibialprosthetic component. As in FIGS. 21-23, the pivot edge of eachextraction instrument is shown abutting the side surface of therepresentative prosthetic component, and pivotal movement of theextraction instrument relative to the side surface of the prostheticcomponent facilitates increased leverage and mechanical advantage, andthus enables improved control in the application of the necessarydisruptive force. FIGS. 26-28 illustrate three representative stages ofthe insertion and use of the J-shaped extraction instrument of FIGS. 3and 4 in the application of reverse axial forces in the removal of theprosthetic component in a direction that is away from the importantanatomical structures (such as blood vessels and nerves) that arelocated in close proximity to the prosthetic component.

The present description includes the best presently contemplated mode ofcarrying out the subject matter disclosed and claimed herein. Thedescription is made for the purpose of illustrating the generalprinciples of the subject matter and not be taken in a limiting sense;the subject matter can find utility in a variety of implementationswithout departing from the scope of the disclosure made, as will beapparent to those of skill in the art from an understanding of theprinciples that underlie the subject matter.

1. An orthopedic extraction instrument for use in revision arthroplasty,the extraction instrument comprising an elongate shaft having a proximalend and a distal end, and an elongate reverse extraction blade connectedto and spaced apart from said proximal end of said shaft by a bridge,said reverse extraction blade extending from said bridge generallyparallel to and in an direction towards the distal end of said shaft,said reverse extraction blade comprising at least one cutting edgedisposed at the free end thereof.
 2. The orthopedic extractioninstrument of claim 1, wherein said reverse extraction blade furthercomprises at least one cutting edge disposed along at least one lateraledge thereof.
 3. The orthopedic extraction instrument of claim 2,wherein said reverse extraction blade has a cross-section that is one offlat, convex and skewed convex.
 4. The orthopedic extraction instrumentof claim 1, wherein said reverse extraction blade is inclined at between0° and 45° relative to the longitudinal axis of the shaft.
 5. Theorthopedic extraction instrument of claim 1, wherein said bridge has across-section that is one of flat, convex and concave along the portionthereof that is disposed toward the distal end of said shaft.
 6. Theorthopedic extraction instrument of claim 1, further comprising a handleat the distal end of said shaft.
 7. The orthopedic extraction instrumentof claim 6, further comprising a striking plate proximally adjacent thehandle.
 8. The orthopedic extraction instrument of claim 7, furthercomprising a slap hammer slidably engaged with said shaft proximal tosaid striking plate.
 9. An orthopedic extraction instrument for use inrevision arthroplasty, the extraction instrument comprising an elongateshaft having a proximal end and a distal end, and a generally planarreverse extraction blade connected to the proximal end of the shaft andextending generally perpendicularly therefrom.
 10. The orthopedicextraction instrument of claim 9, wherein said reverse extraction bladecomprises at least one cutting edge along the edge of the blade that isdisposed closest to the distal end of said shaft.
 11. The orthopedicextraction instrument of claim 9, wherein said at least one cutting edgeis angled relative to the axis of said shaft at an angle of between 75°to 120°.
 12. The orthopedic extraction instrument of claim 9, wherein anotch is formed in said at least one edge.
 13. The orthopedic extractioninstrument of claim 9, further comprising a handle at the distal end ofsaid shaft.
 14. The orthopedic extraction instrument of claim 13,further comprising a striking plate proximally adjacent the handle. 15.The orthopedic extraction instrument of claim 14, further comprising aslap hammer slidably engaged with said shaft proximal to said strikingplate.
 16. An orthopedic extraction instrument for use in revisionarthroplasty, the extraction instrument comprising an elongate shafthaving a proximal end and a distal end, a pivot edge formed at or nearthe proximal end of the shaft, and an elongate extraction bladeconnected to the pivot edge at one of a plurality of inclinations andangles with respect thereto.
 17. The orthopedic extraction instrument ofclaim 16, wherein said pivot edge is flush.
 18. The orthopedicextraction instrument of claim 16, wherein said pivot edge has a heightthat is between 0.5 mm and 15 mm.
 19. The orthopedic extractioninstrument of claim 16, wherein the cross-section of said pivot edge isone of flat, convex and concave along the portion thereof that isdisposed toward the proximal end of said shaft.
 20. The orthopedicextraction instrument of claim 16, wherein said extraction blade furthercomprises at least one cutting edge disposed along at least one lateraledge thereof.
 21. The orthopedic extraction instrument of claim 16,wherein said extraction blade has a cross-section that is one of flat,convex and skewed convex.
 22. The orthopedic extraction instrument ofclaim 16, wherein the axial length of said extraction blade isrelatively short as compared to the length of said shaft.
 23. Theorthopedic extraction instrument of claim 16, further comprising ahandle at the distal end of said shaft.
 24. The orthopedic extractioninstrument of claim 21, further comprising a striking plate proximallyadjacent the handle.
 25. The orthopedic extraction instrument of claim22, further comprising a slap hammer slidably engaged with said shaftproximal to said striking plate.
 26. A system of orthopedic extractioninstruments use in revision arthroplasty of a knee joint, said systemcomprising the orthopedic extraction instruments of at least claims 1, 9and
 16. 27. A kit of orthopedic extraction instruments use in revisionarthroplasty of a knee joint, said kit comprising the orthopedicextraction instruments of at least claims 1, 9 and 16.